1. Field of the Invention
This invention relates to electronic article surveillance (EAS) deactivators for rendering EAS markers inactive, and more particularly to EAS deactivators for deactivating EAS markers on a conveyor.
2. Description of the Related Art
It is customary in the electronic article surveillance industry to apply EAS markers to articles of merchandise. Detection equipment is positioned in interrogation zones at store exits to detect attempts to remove goods with attached active markers from the store premises, and to generate an alarm in such cases. When the articles of merchandise are purchased, the EAS markers are deactivated to prevent detection when exiting the store. There are several types of EAS systems commercially available, including magnetomechanical, RF, harmonic, and microwave.
An example of a magnetomechanical system is disclosed in U.S. Pat. No. 4,510,489. Markers used in magnetomechanical systems are formed of a magnetostrictive element contained in an elongated housing in proximity to a bias magnetic element. The magnetostrictive element is a ribbon-shaped length of a magnetostrictive amorphous material fabricated such that it is resonant at a predetermined frequency when the bias element has been magnetized to a certain level. At the interrogation zone, a suitable oscillator provides an AC magnetic field at the predetermined frequency, and the marker mechanically resonates at this frequency upon exposure to the field. The detection equipment detects the resulting signal radiated by the marker.
In a magnetomechanical EAS marker the bias element functions as a control element. If it is desired to deactivate the magnetomechanical marker, the magnetic condition of the bias element is changed so that the bias element no longer provides the magnetic bias field required for the marker to resonate at the predetermined frequency expected by the detection equipment.
RF EAS systems utilize markers that include a tuned LC resonant circuit. The RF marker responds to an RF interrogation frequency that matches the marker's resonant frequency. The marker's resonant frequency signal can then be detected by detection equipment. RF markers of this type are disclosed in U.S. Pat. No. 5,006,856. To deactivate RF markers, part of the LC resonant circuit can include a fusible member or a breakdown member that, when exposed to high level RF radiation, destroys the LC resonant circuit or changes the LC resonance outside of the range expected by the detection equipment
In retail applications, EAS systems require active markers on merchandise within the retail store. To reduce the in-store burden of attaching EAS markers at the retail locations, the EAS markers described above can be connected to, attached to, placed inside, or in some way associated with articles of merchandise by the article manufacturer or distributor. There is a plurality of different EAS systems presently in use including both RF and magnetomechanical EAS systems. It is desirable for both RF EAS and magnetomechanical EAS markers to be attached to each article by the manufacturer or distributor so that articles arriving at a given store can be detected by the type of EAS system in-use in the store.
When articles are purchased, the EAS markers associated with each article of merchandise will be deactivated. However, the store will have either an RF system or a magnetomechanical system, and, depending on which type of system the store is using, either the RF marker or the magnetomechanical marker will still be active. A patron could thus leave a first store, which utilizes one of the two types of EAS systems and enter a second store, which utilizes the other of the two EAS systems, and set off an alarm.
Presently, there are bulk deactivators available that can deactivate bulk quantities of RF or magnetomechanical EAS markers that are typically used by a manufacturer or distributor. However, bulk deactivators are expensive and can only deactivate one type of EAS marker. What is needed is an economical way to selectively deactivate the appropriate magnetomechanical or RF EAS marker attached to articles at the manufacture's or distributor's site so that when the articles arrive at the retail store, only the EAS markers associated with the store's EAS system type will be active.